System Audit Logs Must Be Group Owned By Root

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Description

All audit logs must be group owned by root user. The path for audit log can be configured via log_file parameter in

/etc/audit/auditd.conf

or, by default, the path for audit log is

/var/log/audit/

. To properly set the group owner of /var/log/audit/*, run the command:

$ sudo chgrp root /var/log/audit/*

If log_group in /etc/audit/auditd.conf is set to a group other than the root group account, change the group ownership of the audit logs to this specific group.

Rationale

Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# Remediation is applicable only in certain platforms
if dpkg-query --show --showformat='${db:Status-Status}
' 'kernel' 2>/dev/null | grep -q installed && dpkg-query --show --showformat='${db:Status-Status}\n' 'auditd' 2>/dev/null | grep -q installed; then

if LC_ALL=C grep -iw log_file /etc/audit/auditd.conf; then
  FILE=$(awk -F "=" '/^log_file/ {print $2}' /etc/audit/auditd.conf | tr -d ' ')
else
  FILE="/var/log/audit/audit.log"
fi


if LC_ALL=C grep -m 1 -q ^log_group /etc/audit/auditd.conf; then
  GROUP=$(awk -F "=" '/log_group/ {print $2}' /etc/audit/auditd.conf | tr -d ' ')
    if ! [ "${GROUP}" == 'root' ]; then
      chgrp ${GROUP} $FILE*
    else
      chgrp root $FILE*
    fi
else
  chgrp root $FILE*
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Get Audit Log Files
  ansible.builtin.command: grep -iw ^log_file /etc/audit/auditd.conf
  failed_when: false
  register: log_file_exists
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Set Log File Facts
  ansible.builtin.set_fact:
    log_file_line: '{{ log_file_exists.stdout | split('' '') | last }}'
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Set Default log_file if Not
    Set
  ansible.builtin.set_fact:
    log_file: /var/log/audit/audit.log
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  - (log_file_exists is undefined) or (log_file_exists.stdout | length == 0)
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Set log_file From log_file_line
    if Not Set Already
  ansible.builtin.set_fact:
    log_file: '{{ log_file_line }}'
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  - (log_file_line is defined) and (log_file_line | length > 0)
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - List All Log File Backups
  ansible.builtin.find:
    path: '{{ log_file | dirname }}'
    patterns: '{{ log_file | basename }}.*'
  register: backup_files
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Apply Mode to All Backup Log
    Files
  ansible.builtin.file:
    path: '{{ item }}'
    group: root
  failed_when: false
  loop: '{{ backup_files.files| map(attribute=''path'') | list }}'
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: System Audit Logs Must Be Group Owned By Root - Apply Mode to Log File
  ansible.builtin.file:
    path: '{{ log_file }}'
    group: root
  failed_when: false
  when:
  - '"auditd" in ansible_facts.packages'
  - '"kernel" in ansible_facts.packages'
  tags:
  - CJIS-5.4.1.1
  - DISA-STIG-UBTU-20-010124
  - NIST-800-171-3.3.1
  - NIST-800-53-AC-6(1)
  - NIST-800-53-AU-9(4)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSSv4-10.3
  - PCI-DSSv4-10.3.2
  - file_group_ownership_var_log_audit
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy